Cellulosic composition of matter containing paraldehyde



Patented Feb. 28, 1933 UNITED STATES PATENT oFFIc STEWART J. CARROLL, OF ROCHESTER, NEW YORK, ASSIGNOR TO EASTMAN KODAK COM IPANY, OF ROCHESTER, NEW YORIQA OORTORATION OF NEW YORK OELLULOSIO COMPOSITION OF MATTER CONTAINING PARALD-EHYDE Application filed September 23, 1929. Serial No. 394,644.

This invention relates to compositions of matter in whichcellulose acetate is combined or mixed with other substances, such as a compatible plasticizer, and a common solvent forboth, with or without other useful addition agents, so that the resulting product Wlll have properties such as will make the composition highly advantageous for use in the plastic and analogous arts, such, for instance, as the manufacture of wrapping sheets, photographic film, artificial silk, varnishes or lacquers, and the like.

One object of this invention is to produce a composition of matter which may be made into permanently transparent, strong and flexible sheets or films of desired thinness which are substantially Waterproof, are unaffected by ordinary photographic fluids and possess the desired properties of a support for sensitive photographic coatings. An-

other object of my invention is toproduce a composition which is capable of easy and convenient manipulation in the plastic and analogous arts, such as in the manufacture of sheets, films, artificial silk filaments, varnishes, lacquers and the like; and to produce a composition which will not injure, or bei11- jured by, the substances or surfaces with which it is associated during manufacture, storage or use. Other and further objects will hereinafter become apparent to those skilled in the art to which this invention pertains. While cellulose acetate has been known for decades it has also been known that to utilize it in the various plastic arts it is necessary to mix therewith such plasticizing or conditioning agents as camphor, triphenyl phosphate, monochlornaphthalene or the like. Certain 49 of these and other addition agentsare also added for the purpose of reducing the infiammability of the product. Plastic inducing agents, such as the higher alcohols and their esters, are sometimes also added. Similarly addition compounds of various kinds have been employed to increase flexibility, transparency, toughness and other properties which will enhance the value of the resulting product. Addition products 50 for the same or similar purposes are also I have discovered that valuable properties may be induced in and/orcontributed to compositions containing cellulose acetate by adding thereto the plastic-izing compound paraldehyde in the presence of a solvent, such as acetone, which will dissolve both the cellulose acetate and plasticizer. This plasticizer is a liquid at ordinary atmospheric temperature and has the formula of (O H O) It is particularly compatible with cellulose acetate in the percentages hereinafter given. It is not an expensive compound and not particularly difliculty to produce, or obtain upon the open market. The particularly useful properties which it induces in or contributes to a cellulosic composition containing it are hereinafter enumerated.

In order that those skilled in this art may better understand my invention, I would state, by way of illustration, that for the manufacture of photographic film or other sheets my new composition of matter may be compounded as follows: 100 parts of acetone-soluble cellulose acetate, i. e. cellulose acetate containing from 36% to 42% acetyl radical, approximately, is dissolved with stirring at atmospheric temperature in, 300 to 500 parts, preferably 400 parts, by weight, of acetone. To this solution may be added from 10 to 50 parts, by weight, of paraldehyde, it being found preferable to employ ap proximately 30 parts thereof. Within the limits stated, the amount of plasticizer may be decreased or increased, depending upon whether it is desired to decrease or increase respectively, the properties which this plasticizer contributes to the finished product.

The amount of solvent employed may also be decreased or increased, depending upon whether it is desired to have a more or ess freely flowing com osition, respectively.

5 A com ositlon o matter prepared as above describe may be deposited upon an suitable film forming surface to form a m or sheet, as is well known to those skilled in the art. A film so produced has permanently l brifliant transparency and low inflammability, burning no more readily than ordinary newsprint. Such film is very tough and flexible as shown b the fact t at it will withstand many fol s upon a modified Schopper fold-tester (commonly used for such purwithout breakin and that even after g subjected for 219 ays to air maintained at a temperature of 65 C. the film still maintains flexibilit demonstrating that the film 2 will withstan ordinary usage satisfactorily for many years, whereas a film formed from a mere solution of cellulose acetate in acetone or other similar solvent is brittle and fragile after bein subjected to the same treatment 2 for as litt e as thirty days or even a lesser time. The sum total of the above advantageous properties of a product produced from m new composition is considerably in excess 0 that of products produced with what have 1 previously been regarded as the better plasticizers.

Other similar solvents (instead of acetone) which are compatible with the cellulose acetate and my new plasticizer may also ocour to those skilled in this art. In like manner this plasticizer may be compounded with other single organic esters of cellulose, such as cellulose propionate, butyrate and the like, or with mixed organic and/or inorganic esters, such as cellulose aceto-stearate, acetomalate, or cellulose nitro-acetate, or with the cellulose ethers, a suitable solvent which will dissolve both the cellulosic derivative and the plasticizer being employed.

The accompanying drawing, forming a part of this application, clearly illustrates the particular advantages of employing my novel plasticizer in the plastic arts. In this drawing there are plotted lines or curves graphically depicting the properties of film produced from a composition containing cellulose acetate and this plasticizer. On the horizontalaxis is indicated the various peroentages of my plasticizer that may be employed with the cellulose acetate, this percentage being given in parts added to the cellulose acetate, rather than parts of the composition; for instance, 30 parts plasticizer 00 added to 100 parts cellulose acetate is denoted as 30% plasticizer added. On the vertical axis at (a), on the left, is indicated in percentage over the check sample the initial flexibility of a film which has been formed as dees scribed from my novel composition and which has been subjected to air at 50 C. for 24 hours to free it of solvent; the rate of combustion of that film is also indicated by this same column (a) at (b) on the right is indicated the length of time in days that the film will maintain flexibility when subjected to air kept at a temperature of C. The curve (A) depicts initial flexibility of the film, the curve (B) depicts the ability of the film to maintain flexibility and the curve (0) depicts the rate of combustion of the film all with various percentages of my novel plasticizer and all as compared to the respective properties of a film produced from a solution of cellulose acetate in acetone and a hypothetical inert material substituted for the plasticizer as denoted by curve (D) indicating unity of 100% and 30 days for (a) and (b) It will thus be noted that my novel plasticizer has the faculty of giving, to a product produced therefrom, very good 'm itial flexibility and a very low combustion rate, and that the product maintains its flexibility quite well. The preferred percentage of my plasticizer which it is desirable to employ to contribute an particular property to the final product Wlll be obvious from an inspection of this drawing; the best percentage to employ will depend upon which property it is desired to feature most in the final product.

Inasmuch as my above described composition of matter is quite useful in the production of films and sheets it will be apparent that my new plasticizer may also be employed with advantage in the other branches of the plastic art. For instance, my above described composition of matter may be employed in the manufacture of artificial silk by the dry spinning method. With the proper coagulating bath it may also be employed for wet spinning. It may be desired to employ a composition of difierent viscosity or evaporation characteristics but this is a mere matter of changing the solvent proportion or adding evaporation retardants such as triacetin or other high or intermediate boiling constituents, as has been well known in the art for more than a decade. My novel plasticizer may also be employed with advantage in connection with a number of the known lacquer and varnish formulae with which it may be found to be compatible. In such cases the plasticizer is usually first put into solution with the cellulose acetate solution and if nonsolvents are added for the purpose of cheapening the composition they are added only to such an extent as will not precipitate the cellulose acetate from solution. Other uses within the scope of my invention will also su est themselves to those skilled in the art.

at I claim as my invention, and desire to be secured by Letters Patent of the United States is:

1. A composition of matter comprising cellulose acetate and paraldehyde as a plasticizer for the cellulose acetate.

2. A composition; of matter comprising parts cellulose acetate and from about 10 to 50 parts, by Weight, of paraldehyde as a plasticizer for the cellulose acetate.

3. A composition of matter comprising 100 parts of cellulose acetate and approximately 30 parts, by Weight, of paraldehyde as a plasticizer for the celluose acetate.

4. A transparent, flexible sheet comprising cellulose acetate and'from about 10 to 50% of paraldehyde homogeneously dispersed throughout the cellulose acetate.

5. A transparent, flexible sheet comprising cellulose acetate and approximately 30% of paraldehyde homogeneously dispersed throughout the cellulose acetate.

Signed at Rochester, New York this 19th day of September 1929.

STEWART J. OARRGLL. 

